WASHINGTON – An apparent smoke bomb was thrown over the fence of the White House as hundreds of Occupy protesters massed outside the gates.

The crowds were dispersed Tuesday night, and U.S. Secret Service spokesman George Ogilvie says there were no arrests in the incident.

However, people inside the White House were being prevented from exiting on the Pennsylvania Avenue side of the building as the situation was being resolved.

Ogilvie says there were 1,000 to 1,500 protesters at one point. He said something appearing to be a smoke bomb was thrown over the fence and that the device was being removed.

Earlier in the day, several hundred protesters converged on the West Lawn of the Capitol to decry the influence of corporate money in politics and voice myriad other grievances.

Organizers had touted the rally, known as Occupy Congress, as the largest national gathering of Occupy protesters to date and secured a permit that would have allowed up to 10,000 people to participate. By mid-afternoon, the protest appeared to have fallen far short of those goals.

Still, participants said they were optimistic about the strength of the Occupy movement, which began in September when protesters pitched tents in a lower Manhattan park. The movement has since spread to dozens of cities, including Washington. While many cities have moved to evict the protesters, the National Park Service has allowed encampments to remain in two public squares near the White House.

“I’m encouraged,” said Jon Wynn, 63, of Snow Camp, N.C., who traveled to Washington to attend the protest and visit friends. “There’s energy here, even if there’s not a whole lot of people.”

The protest comes amid numerous polls that show 84 percent of Americans disapprove of the job Congress is doing, near an all-time low.

While the rally was mostly peaceful, there were some scuffles between police and protesters along walkways leading to the Capitol. By mid-afternoon Tuesday, four people had been arrested _ U.S. Capitol Police said _ one for allegedly assaulting a police officer and three accused of crossing a police line.

The Occupy movement includes activists who want to change government from within and anarchists who oppose all government. Tension between the two camps was evident at Tuesday’s gathering, where some taunted police while others participated in earnest group discussions about how to influence their elected representatives.

Anne Filson, 71, a retired teacher from Madison, N.H., said she was disappointed by the turnout and said Occupy protesters needed to stick to their core message of narrowing the gap between rich and poor. Protesters did not help the cause by carrying profane signs and antagonizing police, she said.

“What I regret about some of the Occupy movements is the dilution of the message,” Filson said. “A lot of Occupy people have to realize that they’re being counterproductive.”

Later Tuesday, small groups of protesters entered House office buildings in a bid to meet with individual members of Congress. Participants also planned to march to the Supreme Court and the White House.

It was not clear whether the out-of-town protesters would swell the ranks of the two Occupy encampments in Washington. Late Tuesday, a House oversight subcommittee announced that it would hold a hearing next week on why the protesters have been allowed to remain in McPherson Square _ which city officials say is infested with rats _ despite a ban on camping on park service property.

Protesters Rachel Marcotte and Taft Clark, 23, planned to return to their tent at Occupy New Haven in Connecticut, which has been compromised by snow.

“We’re told that it’s still up, but it’s not looking good,” Clark said. “We have some work to do when we get back.”